{"created":"2023-06-20T14:35:42.304514+00:00","id":1982,"links":{},"metadata":{"_buckets":{"deposit":"33de9c2d-a049-4108-9593-791c1236067f"},"_deposit":{"created_by":1,"id":"1982","owners":[1],"pid":{"revision_id":0,"type":"depid","value":"1982"},"status":"published"},"_oai":{"id":"oai:jaxa.repo.nii.ac.jp:00001982","sets":["1887:1893","9:10:87:89"]},"author_link":["2022","2023","2020","2021"],"item_3_alternative_title_2":{"attribute_name":"その他のタイトル（英）","attribute_value_mlt":[{"subitem_alternative_title":"Development of a Digital Fluxgate Magnetometer using a Sigma-Delta DAC for Spacecraft Applications"}]},"item_3_biblio_info_10":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"2013-03-29","bibliographicIssueDateType":"Issued"},"bibliographicPageEnd":"80","bibliographicPageStart":"1","bibliographicVolumeNumber":"JAXA-RR-12-008","bibliographic_titles":[{"bibliographic_title":"宇宙航空研究開発機構研究開発報告: デルタシグマDACを応用した衛星搭載用高精度ディジタル方式フラックスゲート磁力計の開発"},{"bibliographic_title":"JAXA Research and Development Report: Development of a Digital Fluxgate Magnetometer using a Sigma-Delta DAC for Spacecraft Applications","bibliographic_titleLang":"en"}]}]},"item_3_description_16":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"人工衛星搭載フラックスゲート磁力計を用いた磁場の「その場観測」は，宇宙プラズマの研究に必要不可欠である．複数衛星による同時多点観測ミッションや木星などの磁気圏探査ミッションでは，搭載機器の重量や電力に厳しい制限がある．磁力計を小型軽量・省電力化するために，1990年代にはディジタル方式フラックスゲート磁力計（以下，ディジタル磁力計と呼ぶ）が開発された．地球磁気圏内外における宇宙プラズマのスケール間結合の解明を目的として複数衛星による同時多点，マルチスケール観測計画（the cross-Scale COupling in the Plasma universE（SCOPE）計画）が進められている．将来の惑星磁気圏探査衛星に搭載するディジタル磁力計にはこれまで以上の磁場分解能（20 ビット）が要求されている．ディジタル磁力計の分解能は信号処理回路に組み込まれるDAC(Dgital-to-Analog Converter)の分解能によって制限される．市販の宇宙用DACは分解能12ビットまでしか製造されておらず，将来ミッションを達成するための高精度ディジタル磁力計に市販の宇宙用DACを用いることは適切でない．本研究ではディジタル磁力計の磁場測定精度を向上させるために，宇宙で使用可能なFPGA（Field Programmable Gate Array）とオペアンプを用いて高精度なデルタシグマDACを独自に設計，開発し，それをディジタル磁力計に組み込むことで精度を向上させた．将来のミッションのために，中間目標として性能（分解能16ビット）を設定し，これを満足するディジタル磁力計を開発した．まず，デルタシグマDACの設計，開発を行い，実験により性能を評価した．次に，そのDACを組み込んだディジタル磁力計(DFG : Digital-type FluxGate magnetometer)を開発し，実験による性能評価によって，デルタシグマDACを組み込んだディジタル磁力計の設計の妥当性を検証した．数値シミュレーションにより分解能16ビットを満足するデルタシグマDACのパラメータを求めた．その結果，オーバーサンプリング比を677 とし，変調器に2次型1ビットデルタシグマ変調器，後置フィルタに4次型アナログローパスフィルタを採用することでデルタシグマDACの分解能が16ビットを満足することが分かった．性能評価試験によって，デルタシグマDACの分解能が18ビットであり，設計値の16ビットを達成していることがわかった．DFGのノイズレベルを測定した結果，ノイズレベルが0.79nT（17.1ビット相当）であることがわかった．開発した磁力計の分解能は，設計値16ビットを満足する結果が得られたことから，デルタシグマDACを組み込んだディジタル磁力計の設計が妥当であるということが実証できた．また，柿岡地磁気観測所における校正試験では，DFGの感度とオフセット，直交度を精度よく求めることができた．DFGを科学観測ロケットS-310-40号機に搭載し，実証試験を行った．観測ロケット実験におけるDFGの役割は，ロケットのスピン周波数を求めること及び地磁気姿勢角（ロケットのスピン軸と磁場のなす角）を求めることである．DFGは，ロケットの打上げからテレメータがロックオフするまでの全期間にわたりデータを取得でき，ロケットのスピン周波数を正確に導出することに成功した．一方，地上校正試験により得られた感度を用いて解析を行い，地磁気姿勢角を算出したが，解析過程においてスピン軸方向の人工的な磁場オフセットが観測期間中に1800nT異なる結果が得られた．しかし，磁場オフセットは時間経過に伴って1800nTも変化しないと考えられるので，フライトデータを用いた感度の校正を行った．地上校正試験で得られた感度とフライトデータを用いて校正した感度から地磁気姿勢角を5度以内の精度で求めることができたが，ロケット実験で要求される2度の精度を下回る結果となった．要求精度を下回った原因として，地上校正試験以降に感度が変化したことが考えられる．DFGを構成する電子部品の温度特性によってDFGの感度は変化する．地磁気姿勢角を精度良く決定するために感度の温度特性を低減すべきである．今後，デルタシグマDAC等の温度特性を実験により定量的に評価することが将来の探査計画の科学目標を達成する上で重要である．","subitem_description_type":"Abstract"}]},"item_3_description_17":{"attribute_name":"抄録（英）","attribute_value_mlt":[{"subitem_description":"Fluxgate magnetometers are most widely used for space science missions to measure the Earth, planetary and interplanetary magnetic field. For future missions (e.g., the cross-Scale COupling in the Plasma universE (SCOPE) mission), it is required to further reduce the resources of instruments as well as to improve the resolution (>20 bits) of the existing magnetometers. The digital-type fluxgate magnetometer has more advantage of being small, light-weight and low power consumption than the conventional types. Its accuracy is determined by the accuracy of the Digital-to-Analog Converter (DAC) in the electronics circuit. The commercial DAC for the space applications does not have better resolution than 12 bits, and is not applicable for the high-resolution digital-type fluxgate magnetometers. As the interim goal for future missions, we designed a 16-bit sigma-delta DAC, in order to improve the accuracy of the digital-type fluxgate magnetometer. The resolution of the sigma-delta DAC depends on the design of the sigma delta modulator and the performance of the analog low-pass filter. It is important to optimize the sigma-delta DAC's design by numerical simulation to achieve the 16-bit resolution. The optimized design of the sigma-delta DAC is described as;  ","subitem_description_type":"Other"},{"subitem_description":"  ・2nd-order 1-bit Boser-Wooley type sigma-delta modulator ,  ","subitem_description_type":"Other"},{"subitem_description":"  ・4th-order, Butterworth type analog low-pass filter,  ","subitem_description_type":"Other"},{"subitem_description":"  ・Over Sampling Ratio is 677.  ","subitem_description_type":"Other"},{"subitem_description":"  The sigma-delta DAC circuit was built using space-use or equivalent parts, and its performance was evaluated experimentally. The resolution of the sigma-delta DAC was approximately 18 bits.The linearity error was better than 0.01 %F.S. The cut-off frequency was 67 Hz. A Digital-type FluxGate magnetometer (DFG) was built using the developed sigma-delta DAC. The resolution of DFG was 0.79 nT which corresponds to the 17.1-bit resolution and satisfies the interim goal resolution (16 bits). The sensitivity and measurement alignment of DFG were accurately calibrated in the magnetic observatory. DFG was installed on the sounding rocket S-310-40 to determine the spin frequency of the rocket and the magnetic field direction with respect to the rocket spin axis. DFG worked successfully and the spin frequency was well determined through the flight of the rocket. However, in the process to derive the angle between the magnetic field and the rocket spin axis, significant (1800 nT) variation of the calculated magnetic offset along the spin axis was found. Since such a large variation of the offset during the flight is improbable, the sensitivity of DFG was calibrated again using the flight data. Based on a comparison of the sensitivity parameters between ground calibration and the flight data, in the case of the S-310-40 experiment, the accuracy of the determined magnetic angle was 5 degrees which does not satisfy the required accuracy (2 degrees). There are several possible reasons why the sensitivity varied after the ground calibration test; e.g. the temperature characteristics of parts used for DFG. The drift of the sensitivity should be reduced for more accurate measurement of the magnetic angle. The temperature characteristics of the sigma-delta DAC should be examined in detail for the development of the magnetometer for future space missions.","subitem_description_type":"Other"}]},"item_3_description_18":{"attribute_name":"内容記述","attribute_value_mlt":[{"subitem_description":"形態: カラー図版あり","subitem_description_type":"Other"}]},"item_3_description_19":{"attribute_name":"内容記述（英）","attribute_value_mlt":[{"subitem_description":"Physical characteristics: Original contains color illustrations","subitem_description_type":"Other"}]},"item_3_description_32":{"attribute_name":"資料番号","attribute_value_mlt":[{"subitem_description":"資料番号: AA0061887000","subitem_description_type":"Other"}]},"item_3_description_33":{"attribute_name":"レポート番号","attribute_value_mlt":[{"subitem_description":"レポート番号: JAXA-RR-12-008","subitem_description_type":"Other"}]},"item_3_publisher_8":{"attribute_name":"出版者","attribute_value_mlt":[{"subitem_publisher":"宇宙航空研究開発機構(JAXA)"}]},"item_3_publisher_9":{"attribute_name":"出版者（英）","attribute_value_mlt":[{"subitem_publisher":"Japan Aerospace Exploration Agency (JAXA)"}]},"item_3_source_id_21":{"attribute_name":"ISSN","attribute_value_mlt":[{"subitem_source_identifier":"1349-1113","subitem_source_identifier_type":"ISSN"}]},"item_3_source_id_24":{"attribute_name":"書誌レコードID","attribute_value_mlt":[{"subitem_source_identifier":"AA1192675X","subitem_source_identifier_type":"NCID"}]},"item_3_text_6":{"attribute_name":"著者所属","attribute_value_mlt":[{"subitem_text_value":"総合研究大学院大学物理科学研究科宇宙科学専攻 : 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)"},{"subitem_text_value":"宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)"}]},"item_3_text_7":{"attribute_name":"著者所属（英）","attribute_value_mlt":[{"subitem_text_language":"en","subitem_text_value":"Space and Astronautical Science, School of Physical Sciences, the Graduate University for Advanced Studies : Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)"},{"subitem_text_language":"en","subitem_text_value":"Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"井口, 恭介"}],"nameIdentifiers":[{}]},{"creatorNames":[{"creatorName":"松岡, 彩子"}],"nameIdentifiers":[{}]},{"creatorNames":[{"creatorName":"Iguchi, Kyosuke","creatorNameLang":"en"}],"nameIdentifiers":[{}]},{"creatorNames":[{"creatorName":"Matsuoka, Ayako","creatorNameLang":"en"}],"nameIdentifiers":[{}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2020-01-15"}],"displaytype":"detail","filename":"61887000.pdf","filesize":[{"value":"5.4 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"61887000.pdf","url":"https://jaxa.repo.nii.ac.jp/record/1982/files/61887000.pdf"},"version_id":"b888e331-f57c-46c4-8bb5-254de17d732e"}]},"item_keyword":{"attribute_name":"キーワード","attribute_value_mlt":[{"subitem_subject":"fluxgate magnetometer","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"sigma-delta DAC","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"plasma physics","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"The sounding rocket mission","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"S-310-40","subitem_subject_language":"en","subitem_subject_scheme":"Other"},{"subitem_subject":"The SCOPE mission","subitem_subject_language":"en","subitem_subject_scheme":"Other"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"jpn"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"technical report","resourceuri":"http://purl.org/coar/resource_type/c_18gh"}]},"item_title":"デルタシグマDACを応用した衛星搭載用高精度ディジタル方式フラックスゲート磁力計の開発","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"デルタシグマDACを応用した衛星搭載用高精度ディジタル方式フラックスゲート磁力計の開発"}]},"item_type_id":"3","owner":"1","path":["89","1893"],"pubdate":{"attribute_name":"公開日","attribute_value":"2015-03-26"},"publish_date":"2015-03-26","publish_status":"0","recid":"1982","relation_version_is_last":true,"title":["デルタシグマDACを応用した衛星搭載用高精度ディジタル方式フラックスゲート磁力計の開発"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2023-06-21T09:31:05.844383+00:00"}